This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. GmpA is a recently discovered non-homologous protein from the assymetrically-dividing procaryote, Caulobacter crescentus, which has been shown to be a critical lynchpin in the establishment and maintenance of cell polarity though its ability to a localize a multi-protein complex which interacts with the origin of replication to maintain the proper subcellular architecture. Analysis of the primary sequence of GmpA shows a 177 amino acid protein with a proline content of over 15%, primarily in the N-terminal region, and a high glutamic acid content contributing to its low pI of ~4.0. Native gels and size exclusion chromatography indicate a higher-ordered oliomeric state when purified from overexpression in E. coli. Evidence of substates under the buffer conditions of purification is also present, though at a much lower level. We propose pilot studies of GmpA using solution x-ray scattering to analyse the oligomeric state of the protein under a wide range of conditions. This will assist in understanding the self-assembly of this complex, explore conditions of maximal protein/protein complex stabilization, and study interactions of GmpA with other proteins that we have identified as interaction partners in vivo.